What is a "part" in a recipe?

When a recipe lists parts instead of measurements, it allows the cook to create as much of the final product as he wants, as long as the ingredients are proportionate. As long as each "part" is in the proper ratio, the final product will be correct.

Some types of cooking are more suited to changing volumes than others. Parts are frequently used in drink or sauce recipes, where the cook may need to create large volumes to serve multiple people. Baking, on the other hand, relies on fairly exact chemistry, making it difficult to increase or decrease the ingredients used without negatively affecting the result.